Calculate the maximum static lateral pressure of concrete + additional horizontal vibration load to get the total horizontal thrust of one side formwork.
Total thrust × safety factor ÷ effective horizontal resistance per shuttering magnet.
Round up the calculation result to get the number of shuttering magnets required for one side.
Sintered NdFeB is hard, brittle, fragile and corrosion-prone. Please note:
① It is strictly forbidden to hit the magnet with external force or damage the anti-corrosion coating on the magnet surface.
② During assembly, the magnet surface is slightly lower than the iron strip plane, which can effectively avoid impact.
③ Stainless steel protective ring process can be adopted to provide physical protection for magnets against collision and corrosion.
1. Do not confuse rated value with effective value: The nominal value of a shuttering magnet is vertical suction force. To resist horizontal formwork expansion force, it must be multiplied by a reduction coefficient of 0.5. It is forbidden to directly use the rated suction as the horizontal resistance design value.
2. Must be installed tightly: The shuttering magnet must be tightly fitted against the side formwork back plate. The suction surface and mold table surface must be cleaned; iron filings and concrete residues will directly cause resistance failure.
3. Bottom is the main resistance area: The resultant point of lateral pressure is close to the bottom surface, so shuttering magnets must be arranged at the rigid back edge at the bottom of the formwork. The upper tie rod only controls opening deformation and cannot replace shuttering magnets to bear horizontal thrust.
② For stubborn attachments such as concrete that are difficult to clean, a grinder equipped with a steel wire polishing disc can be used for polishing and cleaning.
Internal magnet damage: NdFeB is hard and brittle. Cracking due to impact, damage and corrosion of the surface coating will all lead to decreased magnetic performance.
Over-temperature operation: Ambient temperature exceeding the maximum operating temperature of the selected material grade will cause irreversible magnetic attenuation.
In addition, excessive tolerance of assembly screw holes and loose dislocation of iron strips will also cause uneven overall magnetic surface and reduce working suction.